40gr 223 1 in 8

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Chrissmith0881
Posts: 252
Joined: 15 Jul 2014, 15:22
Location: Bakewell

40gr 223 1 in 8

Post by Chrissmith0881 » 19 Sep 2017, 16:39

Just wondering if people have much success with 40gr bullets 1 in 8 twist 223 as i am thinking of trying some.

phoenix
BRUCE ALMIGHTY
Posts: 4752
Joined: 09 May 2012, 14:40
Location: Aberdeen

Re: 40gr 223 1 in 8

Post by phoenix » 19 Sep 2017, 17:18

40gr might be too light for 1 in 8.
1 in 8 tends to be better suited to bullets in the plus 60gr range
40gr could spin so fast that the bullet can withstand the centrifugal forces and literally flies apart.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

RoyR
Posts: 2
Joined: 27 Oct 2015, 08:02
Location: S.E. England

Re: 40gr 223 1 in 8

Post by RoyR » 12 Apr 2018, 16:22

Hello Chrissmith0881,
Just seen this 2017 thread of yours April 2018. Think your 1-8 twist rate should be fine if muzzle velocity is kept below 3700fps
I have two .223 rifles. I use the heavier 60gn loads in the 1-9 twist.
The faster spinning rate of the 40gn V-Max bullet in the 1-9 barrel, causes extra terminal damage on the strike. You can see really serious damage on carcases compared to the 1-12 twist terminal damage.

In .223: I have the T3 Super Varmint S/S 20inch barrel with 1-12 twist, also a CZ527 Varmint 23inch barrel with 1-9 twist.
Well this load below was developed for minimal muzzle flash at night, and works for both rifles with sub 0.5moa ( when I do my bit!) with zero at 200 yards:-

For T3, 20" barrel:-
40gn V-Max
.223 used case trimmed to 1.750" ( we use Lapua)
Sellier & Bellot SR Boxer primer
Vit N120, 23.22gn @ 47881PSI. 1090ft.lbs. Predicted velocity 3500ps in 20 inch barrel with 1-12 twist.
Case fill at 98.7%
Powder burn 99.8% in 20 inch barrel. No muzzle flash at night with moderator fitted.
COAL @ 2.245" Ogive 1.857" (approx .030" off lands)
Crimped neck.
Bullet barrel time 0.812ms. JBM Ballistic Stability - 1.778

For CZ527, 23" barrel:-
40gn V-Max
.223 used case trimmed to 1.750" ( we use Lapua)
Sellier & Bellot SR Boxer primer
Vit N120, 23.22gn @ 47893PSI. 1158t.lbs. Predicted velocity 3611ps in 23 inch barrel with 1-9 twist.
Case fill at 98.7%
Powder burn 99.9% in 23 inch barrel. No muzzle flash at night with moderator fitted.
COAL @ 2.245" Ogive 1.857" (approx .030" off lands)
Crimped neck.
Bullet barrel time 0.883ms. JBM Ballistic Stability - 3.190


Lapua case life with this load is economical. With care 15 plus reloads are possible using just neck sizing.
I use the Ward Thermal 75-3 thermal scope ( BRILLIANT!) mounted on the T3 and this gives approx' bullet drop of 2.5inches @ 250yds and 7inch drop at 300yds
Think that's the most of the useful data.
.
Hope above is of some help.
Regards
Roy

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